cran2deb: extend license handling, specify repository, translate R->Debian package...

cran2deb: extend license handling, specify repository, translate R->Debian package names.

License handling code now deals with version numbers and also the more
common malformed license fields found in the wild.  License version
information is discarded completely at the moment (though retained in
debian/copyright).

debian/copyright also includes a copyright notice formed from the Author
field of DESCRIPTION.

Debian package names must be lower case; the Debian source package
of an R package is the lowercase form of the R package name, whilst the
binary package is r-<lower case repo>-<lower case R name>.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/cran2deb@14 edb9625f-4e0d-4859-8d74-9fd3b1da38cb